Burglar alarm



R. M. BRITT BURGLAR ALARM Nov. 28, 1961 5 Sheets-Sheet 1 Filed Oct. 9, 1957 FIG.1

INVENTOR.

Roberr M. BriH ATTORNEY R. M. BRITT BURGLAR ALARM Nov. 28, 1961 5 Sheets-Sheet 2 Filed Oct. 9, 1957 40' SOUNDER INVENTOR.

Roberf M. Bri'H BY ATTORNEY R. M. B RlTT BURGLAR ALARM Nov. 28, 1961 3 Sheets-Sheet 3 Filed Oct. 9, 1957 FIG.8

FIG.9

INVENTOR.

Robert M. Brifi BY ww d' wm ATTORNEY United States Patent ii 3,011,163 BURGLAR ALARM Robert M. Britt, 240 Abbey St., Massapequa, N.Y. Filed Oct. 9, 1957, Ser. No. 689,211 3 Claims. (Cl. 340-274) This invention relates to burglar alarms and, more particularly, to a novel, compact burglar alarm which, once set off, cannot be silenced by cutting wires or otherwise than by using a re-set key.

In accordance with the invention, a burglar alarm is provided in which all the essential components are contained within a housing or casing which is mounted on or adjacent a door, window, or other closure to be safeguarded. The housing contains a high capacity primary battery, such as dry cells, a sounder, and a self-latching relay which, when operated, locks in a position connecting the battery to the sounder. The relay, when once operated to the circuit closing position, may be reset only by use of a special key for operating the inaccessible resetting mechanism.

In order to prevent inadvertent sounding of the alarm during authorized operation of the safeguarded closure, a selector button or latch is provided which, when moved to the alarm off position before the self-latching relay is energized, opens a switch in the relay energizing circuit. However, this selector button i ineffective to shut off the alarm once it has been triggered by closing of the selflatching relay.

In one embodiment of the invention, the casing is mounted on a door provided with an opening receiving a key operated lock controlling the aforementioned switch in the relay energizing circuit. Thus, when an occupant leaves the premises, the alarm may be set and, upon return of the authorized occupant, the alarm may be rendered ineffective by inserting a key in the lock and opening this switch. Thus, the door may be unlocked and opened without setting off the alarm.

In this embodiment, the detector devices may be located remote from the sounder unit and connected thereto by cables secured to plugs insertable into jack-s in the housing. However, once the alarm has been triggered, even cutting of these lead wires will not shut off the alarm as the relay, when once energized over a circuit including these leads or cables, remains closed until reset, and the alarm energizing circuit is electrically independent of the relay energizing circuit.

In another embodiment of the invention, the unit is entirely self-contained and the alarm is controlled by a micro switch triggered by a sensitive feeler wire. The housing has strong permanent magnets on its base so that the unit may be readily and easily mounted on any paramagnetic metal surface with the feeler wire positioned to detect movement of a safe-guarded closure such as a window, door, or the like. For mounting the unit on a diamagnetic metal surface, or on a non-metallic surface, a paramagnetic metal mounting plate is provided which may be cemented or otherwise secured to the mounting surface. This embodiment includes a latch for locking the feeler wire in inoperative position.

For an understanding of the invent-ion principles, reference is made to the following descriptions of typical embodiments thereof as illustrated in the accompanying drawing. In the drawing:

FIG. 1 is an elevation view, partly in section, of the outside of a door equipped with one embodiment of the burglar alarm of the invention;

FIG. 2 is an inside elevation view of the door with the cover of the alarm housing removed;

FIG. 3 is a side elevation view looking from the right of FIG. 1;

3,011,163 Patented Nov. 28, 1961 FIG. 4 is a view on the line 4-4 of FIG. 2, the cover of the self-latching relay being removed;

FIG. 5 is a schematic wiring diagram of the burglar alarm of FIGS. 1-4;

FIG. 6 is a perspective view of another embodiment of the alarm as mounted adjacent a doorway;

FIG. 7 is an inside elevation view of the cover thereof;

FIG. 8 is an elevation view of the base;

FIG. 9 is a side elevation view of this embodiment; and

FIG. 10 is a bottom plan view thereof.

Referring first to the embodiment of FIGS. l-5, this form of the burglar alarm is mounted within a housing including a base 11 and a removable cover 12. Base 11 is adapted to be secured to a suitable mounting surface illustrated as a door 13. Base 11 is a channel shape member receiving the channel shape cover 12 secured thereto by screws 14, the flanges 16 of the base forming the side walls of the housing and flanges 17 of cover 12 forming the housing end walls. Door 13 is illustrated as having a free edge cooperable with a door jamb 15.

The housing 11-12 contains all the components of the alarm except the detector elements. The detector element 20 for door 13 is mounted in a hole 21 bored edgewise through the door to a position opposite an opening 22 in base 11 to which hole 21 is connected by a crosshole (not shown). "his detector comprises a normally closed switch biased to the open position by a button 23 depressed by janrb when door 13 is closed. Leads 24 in hole 21 and opening 22 connect detector to the energizing circuit of the self-latching relay.

Other detector elements, such as 20, may be located remotely from the alarm housing and provided with leads 26 connected to plugs engageable in jacks 27 in one flange 16 of base 11. Jacks 27 are connected in parallel with the leads 24. Detector elements 20 may be located, for example, at other windows or doors to be safeguarded by the alarm.

The components of the alarm mounted on base 11 comprise a high capacity dry cell battery 30, secured to base 11 by a strap 31, a switch mounted on a bracket 32, a sounder mounted on a bracket 33, a test push button mounted in a flange 16, and a self-latching relay mounted on the other flange.

Switch 35 is connected in series in the energizing circuit of relay 50, and is illustrated as a toggle switch whose handle 34 has connected thereto a selector button 36 pro jecting outside the housing. When button 36 is pulled out, switch 35 is closed to set the alarm, and switch 35 may be opened to inactivate the alarm when button 36 is pushed in.

Switch 35 may also be operated from outside the door by inserting a special key into a lock 37 set into door 13 and having a flat bar 38 turned by the key. The inner end of this flat bar has a pair of radial arms 39 arranged to engage and operate switch handle 34. Thereby, upon leaving the premises, button 36 may be pulled out to close switch 35 and, when the occupant returns, the switch 35 may be opened by turning the special key in lock 37.

If desired, the operative condition of the relay circuit may be controlled from a location remote from the alarm by a switch unit 35' having an operating knob 36' and connectible in series with switch 35 by inserting a plug 41 into a jack 42 in a base flange 16, switch 35' being connected to plug 41 by leads 43.

Self-latching relay 50, after being energized, can be re-set to shut off sounder 40 only by inserting a special key 44 into a lock 46, on a flange 16, to turn an abutment 47 to engage and depress re-set button 51 of relay 50.

Referring to FIGS. 4 and 5, self-latching relay 50 includes energizing coil means 52, an armature 53 and a permanent magnet 55. Armature 53 is connected to one terminal of battery 30 and normally engages a back contact 54 connected to one terminal of the coil means 52. The other terminal of the coil means is connected through switch 35, and jack 42 or switch 35', to one side of the parallel detector circuits, the other terminal of battery 30 being connected to the other side of these circuits and to sounder 49 through conductor 56. Conductor 57 connects sounder 40 to permanent magnet 55.

The operation of the alarm will be explained with particular reference to FIG. 5. To set the alarm, switch 35 is closed and also switch 35', if the latter is used. This is effected by pulling out buttons 36, 36 or by pulling out button 36 and turning lock 37. Should door 13, or any closure safeguarded by a detector component 26, be opened by an unauthorized person, relay 50 is closed over the following circuit: battery 30, armature 53, back contact 54, coil means 52, switch 35, switch 35, detector 20 or 20', and the other side of battery 30.

Relay armature 53 is picked up, disengaging contact 54 to open the relay energizing circuit. Armature 53 moves into the effective field of permanent magnet 55 and engages the latter. Sounder 40 is energized as follows: battery 39, armature 53, permanent magnet 55, condoctor 57, sounder 40, conductor 56, and battery 30. The sounder is thus energized over a circuit included within housing 11-12 and independent of detectors 2%, 29 or their leads, buttons 36 or 36, and lock 37.

The only way to shut off the sounder is to insert key 44 into lock 46 to turn abutment 47 to depress re-set button 51 of the relay. This pushes armature 53 away from permanent magnet 55 and out of its effective field. It should be understood that the permanent magnet type of relay is exemplary only, and that a mechanical latch may be provided for armature 53. Such a relay is illustrated in FIG. 4 wherein a latch 58 engages armature 53, when the latter is picked up, latch 58 being releasable only by depressing re-set button 51.

Test button 45 is connected between battery 3% and sounder 40 so that the condition of the battery and sounder may be readily tested by depressing button 45.

FIGS. 6 through illustrate a portable or self-contained embodiment of the burglar alarm. Base 111 has secured thereto a pair of strong permanent magnets 60 by means of which the unit may be mounted on a paramagnetic metal surface. For mounting the unit on diamagnetic metal surfaces, or on non-metallic surfaces, a relatively lightweight paramagnetic metal mounting plate 65 is cemented to the surface for cooperation with permanent magnets 66.

The alarm is triggered by a sensitive feeler wire 7% projecting through a slot 161 in cover 112 and operating a micro-switch 120 mounted inside the cover. A pivoted latch 75 is mounted on cover 112 to lock wire 70 in the ofi position of switch 120 to deactivate the alarm. In use, the unit is mounted, for example, on a door jamb so that feeler wire 70 is in movement detecting relation with a door 13'. To set the alarm, latch 75 is moved to the release position.

Any movement of door 13 results in corresponding movement of feeler wire 70 to close switch 120 to energize the alarm. If desired, the alarm could be mounted on door 13 with feeler wire 78 engaging door frame 15'. The main feature of this embodiment of the alarm is that it may be readily and easily mounted on any surface and transferred to different locations, if desired, without re-wiring.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is' claimed is: I

1. A burglar alarm comprising, in combination, a housing; an electric power source; a sounder; a latching relay including operating coil means, an armature operable by said coil means, a back contact engaged by said armature in the dropped position thereof, a front contact engageable by said armature when said coil means is energized, and latch means operable to hold said armature engaged with said front contact when said armature has been picked up by energization of said coil means to disengage said back contact; a detector device including a normally closed switch biased to the open position by a safeguarded closure in the closed position of the latter; reset means operable to release said armature from said latch means; a first energizing circuit, for said relay, including said source, said detector device, said coil means, said back contact and said armature in series with each other; and a second energizing circuit, for said sounder, including said source, said sounder, said front contact, and said armature in series with each other; whereby, upon opening of said safeguarded closure, said second circuit will be closed and remain closed until operation of said re-set means.

2. A burglar alarm comprising, in combination, a housing; an electric power source; a sounder; a latching relay including operating coil means, an armature operable by said coil means, a back contact engaged by said armature in the dropped position thereof, a front contact engageable by said armature when said coil means is energized, and permanent magnet means operable to hold said armature engaged with said front contact when said armature has been picked up by energization of said coil means to disengage said back contact; a detector device including a normally closed switch biased to the open position by a safe-guarded closure in the closed position of the latter; re-set means operable to release said armature from said permanent magnet means; a first energizing circuit, for said relay, including said source, said detector device, said coil means, said back contact and said armature in series with each other; and a second energizing circuit, for said sounder, including said source, said sounder, said front contact, and said armature in series with each other; whereby, upon opening of said safe-guarded closure, said second circuit will be closed and remain closed until operation of said re-set means.

3. A burglar alarm comprising, in combination, a housing including a base and a cover mounted on the closure to be safe-guarded; an electric power source mounted in said housing; a sounder mounted in said housing; a latching relay mounted in said housing including operating coil means, an armature operable by said coil means, a back contact engaged by said armature in the dropped position thereof, a front contact engagea-ble by said armature when said coil means is energized, and latch means operable to hold said armature engaged with said front contact when said armature has been picked up by energizetion of said coil means to disengage said back contact; a detector device including a normally closed switch biased to the open position by the safe-guarded closure in the closed position of the latter; re-set means operable to release said armature from said latch means; a lock in said housing having a movable element operable, upon operation of said lock by a key, to operate said re-set means; a first energizing circuit, for said relay, including said source, said detector device, said coil means, said back contact and said armature in series with each other; and a second energizing circuit, for said sounder, including said source, said sounder, said front contact, and said armature in series with each other; whereby, upon opening of said safe-guarded closure, said second circuit will be closed and remain closed until operation of said re-set means.

Sturts Feb. 28, 1893 Pincus et al July 10, 1964 (References on following page) 5 6 UNITED STATES PATENTS 716,896 Germany Jan. 31, 1942 2,057,301 Golokow et a1. on. 13, 1936 579,150 Canada July 1959 2,526,2Q6 B01311 Oct. 17, 1950 OTHER REFERENCES ga 536131617 5 5 5 Text: Relay Engineering, FIG. 101, page 212, ccpyright gi' ggi g i ig 1945 by Smithers-Dunn, Inc, Phiiadeipizia, Pa.

, 3,: "I 1 L K16 /O FOREIGN PATENTS 114,616 Switzerland Mar. 1, 1926 

